1. Field of the Invention
The present invention relates to golf balls. Specifically, the present invention relates to processes for designing a rugged pattern on a golf ball surface.
2. Description of the Related Art
Golf balls have a large number of dimples on the surface thereof. The dimples disturb the air flow around the golf ball during flight to cause turbulent flow separation. By causing the turbulent flow separation, separation points of the air from the golf ball shift backwards leading to a reduction of drag. The turbulent flow separation promotes the displacement between the separation point on the upper side and the separation point on the lower side of the golf ball, which results from the backspin, thereby enhancing the lift force that acts upon the golf ball. The reduction of drag and the enhancement of lift force are referred to as a “dimple effect”.
The ratio of the total area of dimples to the surface area of a phantom sphere of a golf ball is referred to as occupation ratio. It is known that the occupation ratio correlates to flight performance. A golf ball having an increased occupation ratio is disclosed in U.S. Pat. No. 5,292,132 (JP4-347177). The golf ball has circular dimples.
In a golf ball in which a small circular dimple is arranged in a zone surrounded by a plurality of large circular dimples, a high occupation ratio can be achieved. However, the small dimple does not contribute to the flight performance of the golf ball. There is a limit to the dimple effect of the golf ball having the circular dimples.
US2013/0005510 (JP2013-9906) discloses a golf ball having a dimple pattern designed by a Voronoi tessellation. The golf ball has a large number of non-circular dimples. The occupation ratio of the golf ball is high.
U.S. Pat. No. 7,198,577 discloses a golf ball having hexagonal dimples. The occupation ratio of the golf ball is high.
In the golf ball disclosed in US2013/0005510, variations of the areas of the dimples are great. The dimple effect of the golf ball is not sufficient. There is room for improvement in the flight performance of the golf ball.
In the golf ball disclosed in U.S. Pat. No. 7,198,577, the dimples are orderly arranged. The dimple effect of the golf ball is not sufficient. There is room for improvement in the flight performance of the golf ball.
An object of the present invention is to provide a golf ball having excellent flight performance.